Hi Andy,A switcher may be a bit over the top. You'll see what I mean when you have a go with the board. Earthing a pin puts the function on.

It would be possible to activate 3 micro switches or push buttons with a servo arm to get the functions. If this seems a little in-elegant, the PWM version should not be too many weeks away!

My first thoughts were to see if the fish swims forward, right left etc. (I still find it hard to believe!) and if a servo is powerul enough So maybe we should aim for an initial "lash-up" trial in the home test tank!

The three small boards to the bottom right are some little switchers I'm making up. These trigger the various functions on the PIC board.

I did find an off-the-shelf switcher, which is tiny and cheap. However I considered the means of controlling the switching didn't quite work for the fish. So I looked around for an alternative.

These baords are designed by Ken Hewitt. The design can be downloaded here, and it is very simple and cheap (about £1 per switch) to put together. I'm waiting for some more components to arrive to finish the boards off, which should hopefully arrive in the next couple of days.

I'm using a much smaller logic level MOSFET for the switches, than specified in the design. The original was overkill for this application.

They are bulkier than a commercial design, but that isn't an issue as I have plenty of room inside the fish.